Compensated absolute-pressure gauge



April 16, c w BRISTQL COMPENSATED ABSOLUTE PRESSURE GAUGE Filed June 1928 2 Sheets-Sheet l INVENTOR ATTORNEY Patented Apr. 16, 19 29.

UNITED 'srATEs' PATENT, OFFICE.

CARLTON w. BRISTOL, OFTNAUGATUCK, CONNECTICUT, ssIGNoR TO'THE BRISTOL COM- PANY, or WATERBURY, couuuc'rrcu'r, AHCORPORATION or conNEc'rIcUT.

COMPENSATED ABSOLUTE- PRESSURE GAUGE.

' Application filed June 1',

urement of absolute pressures such as pre vail, for example, in. condensers and the ibsolute static pressures of gas lines equipped with flowmetei's. Y

In carrying'out this inventiomthe Bour-. don tube is monstructed of twonon-coinmunicating butconnected sections, oneof which'i-s rigidly secured at one end and arranged to communicate at this point with the fluid whose pressure is to b e determined while the other substantially evacuated and has connected with-itsffree end a measuring member or pointer for indicating or recording the changes in fluid. r

The nature of the invention, however, will best be understood when described in connection with the accompanying drawings, in which; 1 F ig. 1 is a front elevation of an indicating pressure gauge connected to a source of flu (1 whose pressure it is desiredto ndlcateon the said gauge; I i

, 2 is a side elevation, on an enlarged scale, of the actuating and' compensated I Bourdon tube utilized in the novel absolute:

y no

and arranged about and coaxially with the said first-named. section 10.] The latter at itsinner end is secured to'a bracket 13 01; other y-fi'xed support and is provided :also

withan opening or connection l4 whereby communication may'be zhad, as through a suitable connecting tube'15, betweenthe interiorjofgsaid section andaj source of fluid pressure oflthe 1928. Serial No. 282,247.

supply represented bythe pipe l6, forex ample, of a gas line. The outer or compensating section 12, does not communicate with the interior of the section 10;. and, furthermore, it issealedat its inner endl7 to which substantially to complete vacuum.

The whole actuating; mechanism 'herein- '80 is-secured, preferably directly, themeasuring v arm or pointer member 18. The said section, I furthermore, 18 arranged to be evacuated before described is mounted and enclosed with a suitable casing QO'haVing a gradu= signed to .move to indicatethe different pres-, sures infaccordanc'e withthe conditions prevailing in the fluid supply sourcelfl.

In.'tl1e operation ofmeasuring apparatus ated dial .21 over which pointer 18isfdeembodying the Bourdon type of actuating ject to variations in the pressure of the sur-' rounding atn'iosphere and errors will be introduced therebyin the indicationsafforded' by, the instrument of the pressure of the fluid to which said instrument is connected. In

acfordance with the invention and morepa a ticularly through the provision of the com pensatingsection 12 of the tube,- the effect I off the pressurejvar ations 1n. the surroundring-atmosphere are neutral zed, more espemember, it will be'appreciated that the tendency of such tubes is to straighten out or uncoil under the influence of internal pressure cially in View of; the fact that said section, i belngwound infth'es'ame direction as the actuating section {10, operates-to move the J pointer-member18. over the scale 21in a dig rection opposite to that which the actuating section would move the same under similar pressure changes in the surrounding atmospherefand .in equal amounts for the same change; i

Th-is will secure a correct'indication of-the' absolute-pressure applied. to the actuating loo section through the connection 16 I thereto; I- i and there 1s, furthern'iore, no disturbing cf fectdueto variations in temperature on the compensatin v section since the latteris' subs stan'tia'lly evacuated. By thisexpedient,

;,ently"mounted'tubes and 26 are provided, the former being secured at its inner end to a back or supporting casing plate 27, while the latter tube is rigidlyconnected at its inner end to a shaft 28 mounted to oscillate on the plate 27. The arrangement is sucln moreover, that thefree ends of the two tubes move in opposite directions with similar changes in applied 'Pl'6SSllI'SL' The said ends, moreover, are interconnected in the following manner so that the one tube, astube 26, which is the substantially evacuated] one, may serve to apply the requisite correction to the other, which 1S to be connected with the source of fluid whose variations in pressure it is desired to. measure.

To this end, a linkage system is included between the two saidgtubes and embodies the radially ex ten'ding arm 29 movable wit a shaft 30 secured rigldly to the free end of tube 25 and located axially therein. The

tube 26, likewise, carries an arm 32 which is adapted to partake of angular movement of the shaft 28; and the twoarms 29 and 82 are connected at their outer ends by means of a link so that angular movementot either tube will be communicated to the other. The indicating pointer 34, however, is to be connected with the evacuated tube 26, asat its free end 35, forexample, by

means of an arm 36 attached thereto and. connected by meansoit a link 37 with a crank arm 38.. The latter extends from an indicator arm shaft 40 which is rotatably mounted on thecasing, whereby changes of pressure, occurring at normal atmospheric pressures, within'the tube 25 will cause corresponding movement of the said indicator arm; but if the atmospheric pressure departs from the normal, tube 26 will be correspondingly affected and the movement. of its freeend 35 will resistor'increase accordinglythe movement communicated by said tube 25 and thus compensate the same to the normal pressure. a

"In initially setting the novel gauge, the pointer is 'adjustecL-for example, to readlk? lbs. "absolute on the scale, withbarometric gpressureat 30inches of mercury, and with the open end of the tube .infdirect communication with the atmosphere; When connected to asource of pressure, if a change section embodying the the external atmosphere surrounding the tube and mau e then occurs sa above the a m 7 I 14:. lbs. this would normall cause the pointer to move below the correct point on the scale corresponding to the apphed pressure; but in the present embodiments, the

compensating section of the. tube will also be equally affected thereby. Since this section operates 'to move the pointer in the reverse direction, the error will be balanced and a correct indication afforded.

I claim: r 1(Absolute-pressure gauge of the Bourdon tube type, embodyinga Bourdon tube having one'end secured to receive the fluid whose pressure it is desired to measure, and

a substantially evacuated extension con-,

nected with the other end-and whose other end is free, said tube and extension being of equal strength and mounted to move in directions to oppose each other for like atmospheric or surrounding pressure changes to which they may be exposed, and an arm member Jnnected with the free end of said evacuated extension.

2. Absolute-prcssure gauge, comprising a Bourdon tube with secured end and free end and having two connected non-communicating sections of equal strength and coiled to oppose each other, and the onesection embedying the free end being substantially completely evaci'iated, and the otherand secured end adapted for connection to source oi fluid supply to receive fluid whose pressure is to be measured, and an arm member'connectedwith the free end of the said tube and-responding to angular movement thereof. a r n ibsolute-pressure gauge, comprising a Bourdon tube with secured end and free end and'having two non-communicating sections of equal strength coiled in the same direction the one within the other, and the one p *ee end being substantially completely evacuated, and: the other and secured section adapted for con his nectionto a source of fluid supply to receive fluid-whose pressureis to be measured, and

an armniemberconnected with the freeend of the saidtube and responding to angular movement thereof.

4i;Absolute-pressure gauge, comprising a Bourdon' tube sealed intermediate its ends and at one end, the sealed-oil portion being substantially completely evacuated and of equal. strength with the remaining portion, and the other and open "end being secured and adapted for communication with a source of fluid-whose pressure is to'be measured, and an arm member secured-l to the 7 free end of said tube responding" to n l movement thereof. a 7

In'testimony whereof I afliX my signature.

CARLTON- w. BRISTOL. 

